Eagle eyed people who watch who registers what domains have noticed that Google have registered (via a proxy) googlecheckout.net.
Some commentators think this may be an indication that this may be Googles version of paypal
Garett Rogers at zdnet comments
“I think it will be a shopping cart system to help websites accept payment for their items on line. The money site owners make will be deposited into a holding account at Google — just like ad sense works.”
I think that this is a plausible and could give website owners an extra way of integrating payment into their sites and if it linked up with ad sense, froogal and google base could almost provide a full online shop.